Electric switch



C. H..HILL.

ELECTRIC SWITCH.

APPLICATION man MAY5.1916.

IIIII lllllii lll/Iliff',

Patented Apr. 12

1^| le, Attorney UNITED STATESPATENT oFFlcs.

CHARLES H. HILL, OF SCHENECTADY, NEW YORK/ASSIGNORTO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC SWITCH.

Specification of Letters Patent.

'Patented npr. 12, 1921.

Application filed May 5, 1916. Serial No. 95,596.

protection of human life that the live parts of the switch be entirely protected in such a way that an operator` cannot touch a switch to replace a fuse or the like until the switch has been opened and cannot close the switch while there is danger of touching live parts. Furthermore, it is also very desirable that when the switch f has been opened by the operator in order to make some repairs in the machine or similar ap-Y y paratus which may for instance be operated by a motor'controlled by the switch, that some other person cannot close the switch and start the machine while the operator is repairing or adjusting his machine and is for the time being perhaps concealed from view.4

It is the object of my invention, ther/e-` fore, to provide a novel and improved electric switch which embodies these safety irt principles while the particular object of my invention is to provide a switch in which the parts thereof cannot be touched until after the switch is" opened and the' switch cannot be closed while there is a possibility of one touching live parts. Furthermore, it is the object of my invention to provide a switch which can be locked in open position and in which the switch is so` arranged that an operator cannot get 'at the switch mechanism without authorization to o so.

The novel features which I believe to be characteristic of my invention will be deined in the claims appended hereto, the features of construction and mode of operation being understood by reference to the following'description taken in connection with the accompanying drawings, in which z- Figure 1' shows a front elevation partly applied to in section of a switch embodying the novel features of my invention, Fig. 2 is a sectional end elevation taken along the line 1-1 of Fig. 1 with a portion taken away for the purpose of clearness, Fig. 3 is an end elevation of my novel switch and Fig. 4 1s a perspective view of a detail of construction.

In Fig. 1, I have shown, by way of example, the novel features of my invention a two pole knife blade switch havlng a movable switch member comprising the 'contact blades 1 connected by a bar` of insulating material 2 to enable the con- 'tacts to be operated simultaneously into and out of engagement with cooperating fixed contacts 3. The switch is mounted in a ,metal protective casing or box 4 which completely incloses the switch. Themovable switch blades 1 and contacts 3 are mounted in'the upper part of the casing, the casing being provided with an enlarged portion 5 into which the contact blades are movable upon moving to switch opening position. This portion of the switch casing is closed and protects the live parts of the switch. Below the contact blades 1 and in electrical connection therewith are suitably mounted the usual fuse members 6. This portion of the casing is closed by a hinged or pivotally mounted cover or opening member which can be opened to replace a blown or disabled fuse but which provides no way of getting into touch with switch mechanism.

For actuating the switch I provide a bowed rock shaft or yoke member 8 pivot-- ally `supported or journaled onopposite endsy of the casing 4 carried at one en y `a trunnion and at the other end on \a\shaft a member 12 movable by the handle 10 and 13 having a curved or convex engaging surface. This lug 13,

carrying thereon a lug carried by the operating member 10, coperates with a flange orA lug 14 'carried on a member 15 and movable by the cover 7. Lug 14 has a cooperating curved or concave engaging surface with which the curved surface of lug 13 engages to form an i'nterlocking means or mechanism for the switch.

The operation of the switch structure so far described is as follows: Let us consider the switch as in closed position, as shown in Figs. 1, 2 and 3, theoperating member 9, being in the switch closing position as shown in Figs. 1 and3 with the lug 13 carried by the handle, in the position shown in Figs. 1 and 2. The cover 7 ofthe protective casing 1 for the switch is shown in closed position, in Fig. 2, with its lug 14 in the position it assumes when thecover is closed. With the switch4 in closedposition, it is essential as a safety feature that the cover cannot be opened and this is accomplished by the relation existing between the lugs 13 and 14 when the handle 9 is in switch closing position. It will be observed if an'attempt 1s made to open the cover 7 its lug 14 engages lug 13 and prevents the opening because the lug- 13 in the switch closing position of the handle 9 is in the path of movement of lug 14, or the lugs 13 and 14 are in cover-locking position or relation. The switch, however, can be opened at will by moving the handle l0 from the. on position shown in Fig. 3 to the off position through which movement the contact blades l are carried by the yoke 8 and arm 11 through the enlarged portion 5 of the casing shaped for the purpose. In moving the switch to opening position the handle 9 carries its lug 13 out of the path of movement of lug 14. Hence when the switch is open, the cover 7 may be opened, the opening of the covercausing the curved` surface of its lug 14 to slide over the now substantially concentric curved surface of lu'g 13 to assume the position shown in Fig. 4, the two coperating surfaces of lugs 13 and 14 beingl in interlocking engagement. When the cover is open, the handle 9 cannot be moved to switch closin yposition vbecause the lugs 13 and 14 are t en in switch-locking position .or relation as lug 14 carried by the cover 7 is then in locking relation or engagement with lug 13 and it is impossible to move lu 13 and hence the handle 9 to close the swltch. With this novel interlocking construction I provide a'switch which must be opened before the coverof its protectin casing can be opened thus assuring that t e operator cannot get at the switch' whilethe partsv are alive-and at the same time the switch cannot be closed to 'render its parts alive until the cover has been closed to protect the same.-` The casing is also constructed so that only the fuses are available to the operator when he opens the cover, the switch mechanism being in the upper part of the-casing which cannot be reached. An operator can therefore replace a blown fuse in his switch and in doing so is always protected yfrom live parts of the switch.

In practice such aswitch 'as described is often used to control the circuit of a motor operating a machine of some sort. Suppose the operator opensthe switch to make some repairs or adjustments on this machine andthen gets under the machine or otherwise conceals himself from vievv'jin his Work on the machine. If the switch was accidentally closed while he was in such a position, it would result in 4his injury. -To safeguard the operator under these conditions, I provide an offset locking portion or member 16 carried by and movable with the cover 7 being, preferably substantially -U-shaped and provided with two holes 17 and 18, as best shown' in Fig. 1. Coperating with this member 16 is an offset member 19 carried on or secured to the switch casing 1 and provided with an opening adapted to register with opening 17. The

an offset portion or member 20 provided Withl a hole 21 which is adapted to register withy opening or hole 18 on member 16.

In the position shown in Fig. 3, the switch is 'closed and the cover is closed. In this position hole 17 of member 16 and the open- -ing in member 19 are 1n alinement and are ,casing cover to replace fuses or do other repairs. f

When the switch is open, the operating member is in lswitch opening or off position and in this position, the hole 2l inthe offset member 20 carried by the operating arm registers with or is in alinement with handle or operating member 9 carries also the hole or opening 18 in the offset member 16. The operator is provided with a lock which he can then insert through the registering holes 21 and 18 and lock the switch in the open position. He Ais then free to repair the machine or adjust it Without any danger of any unauthorized person closing the lswitch and subjecting him to possible injury. At the same time the insertion of the operators lock inthe registering holes 21 and 18 prevents the electrician from' o ning the cover 7 even after he removes his lockfrom the members 16v and 19 due to the factthat the operators lock is holding v is closed to preven 7 and before Athe cover can Y must remove his lock. embodied in many the cover opened the operator My invention may be other forms than that shown and described and I, therefore, do not wishl to be restricted to the precise construction disclosed, but intend to cover by the appended claims all changes and modifications witwspirit and scope of my invention.

What I claim as new and desire to secure by Letters Pat/ent of the United States, is

1. In an 'apparatus of the class described, .a switch, a casing inclosing said switch, a lever adapted to be operated to open and close said switch, a lug mounted to move with said lever and provided with two opposed convexly curved faces, a cover hinged to said' casing, and a curved flange on said cover arranged so that one end thereof abuts one of the faces of said lug when the switch t o-pening said cover, said lug being mounted to move out of abutting engagement when the switch is opened to permit the movement of said flange over the other face of said lug whereby the switch cannotbe closed when the cover is open.

2. In an 'apparatus of the classv described, a switch, a casing inclosing said switch, a lever adaptedto be operated to open and close said switch, a cover hinged to said casing, a` curved flange on said cover, a lug mounted to move. with said lever, ized b-y the fact that said lug is provided with two opposed curved faces, one of said' faces being 1n abutting engagement with one character- 

